hi folks, scratching my head with this one... please help 
MB: 820-2914-A
history: just turned off, no watermarks
initial issue: short on PPBUS_G3H - gone by removing elements in the GPU power rail path
current issue: pulsing most of S3+ rails ( and PM_SLP* ) - every few seconds. Pulse lenght about half a second.
found/fixed so far:
- shorted GPU (now removed all the power to it - coils, U8900, some FETs)
- U7201's P3V3S5_PGOOD (S5_PWRGD) - all time ok
- U7201's P5VS3_PGOOD - on for a very short spike (ms)
- no shorts on other coils (especially CPU ones)
going PP5V_S3 path (which produces PP5V_S0) all checked out with exception of U7100, which exhibits behavior similar to that of U7201:
- PVCCSA_PGOOD - very short spike (ms)
- FB pins 7/11/12 - longer pulse (hundreds of ms)
- pin 5 (CPU_VCCSA_VID) 1.05V
So to sum up - the enable signals are there for longer period (half a second), which translates to very short (ms) PGOOD signals for PP5V_S3 / PP5V_S0, which translates into a power loop.
No short on PPVCCSA_S0_CPU. Regular 1.05V pulsing as above (half a second output).
Thing which is off about U7100 is that there is a voltage divider between pins 7,8 & 9. I am not getting anything on the 'bottom' of R7148 (pin 2), even though the resistor itself checks out as 140K and has 0.51V on pin 1. Not sure if this is at all related...
What gives?
MB: 820-2914-A
history: just turned off, no watermarks
initial issue: short on PPBUS_G3H - gone by removing elements in the GPU power rail path
current issue: pulsing most of S3+ rails ( and PM_SLP* ) - every few seconds. Pulse lenght about half a second.
found/fixed so far:
- shorted GPU (now removed all the power to it - coils, U8900, some FETs)
- U7201's P3V3S5_PGOOD (S5_PWRGD) - all time ok
- U7201's P5VS3_PGOOD - on for a very short spike (ms)
- no shorts on other coils (especially CPU ones)
going PP5V_S3 path (which produces PP5V_S0) all checked out with exception of U7100, which exhibits behavior similar to that of U7201:
- PVCCSA_PGOOD - very short spike (ms)
- FB pins 7/11/12 - longer pulse (hundreds of ms)
- pin 5 (CPU_VCCSA_VID) 1.05V
So to sum up - the enable signals are there for longer period (half a second), which translates to very short (ms) PGOOD signals for PP5V_S3 / PP5V_S0, which translates into a power loop.
No short on PPVCCSA_S0_CPU. Regular 1.05V pulsing as above (half a second output).
Thing which is off about U7100 is that there is a voltage divider between pins 7,8 & 9. I am not getting anything on the 'bottom' of R7148 (pin 2), even though the resistor itself checks out as 140K and has 0.51V on pin 1. Not sure if this is at all related...
What gives?
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